Inert Gas Narcosis: Avoidance Behavior in Rats Breathing Elevated Pressures of Nitrogen and Helium.

摘要

Avoidance response rates generated by a free-operant avoidance schedule with a response-shock interval of 20 sec and a shock-shock interval of 2 sec increased when rats breathed raised pressures of nitrogen up to 19 times normal atmospheric pressure. Further, nitrogen pressure increases to over 30 times normal pressure produced decreases in avoidance rates and disruption of temporal discrimination reflected by changes in conditional probabilities of interresponse times. Changes in avoidance response rates and shock frequencies were related to increases in nitrogen partial pressures rather than total absolute pressure as oxygen and carbon dioxide partial pressures were kept at normal atmospheric levels, and similar avoidance performance changes did not occur at identical pressures breathing helium. Increased helium pressures produced increases in avoidance responding at 26 to 30 times normal atmospheric pressure that were similar to effects of nitrogen at lower pressures, indicating that nitrogen is about four times as potent as helium in terms of narcotic effects on avoidance behavior. (Author)